TWI521785B - Frequency selective surface (fss) structure for improving the quality of wireless communication - Google Patents

Description

Frequency selection plane structure for improving wireless communication quality

The present invention relates to a planar structure, and more particularly to a planar structure suitable for frequency selection.

In recent years, environmental awareness such as energy conservation has been deeply rooted in people's minds, and various modern buildings have adopted special building materials to save resources, such as energy-saving glass. The energy-saving glass is manufactured by coating a layer of metal oxide on the outer layer of the general glass, and using the layer of metal oxide to insulate the energy flow into and out of the building for a long time, thereby achieving the effect of saving heating consumption in the winter and cooling air consumption in the summer. However, the metal oxide layer on the energy-saving glass will also attenuate the signal of wireless communication, resulting in a decline in communication quality. Due to the increasing demand for wireless communication in modern office buildings, there is an urgent need for new improvements to make energy-saving glass. The metal oxide layer can achieve energy-saving effects and maintain good wireless communication quality.

Frequency selective surface (FSS) has many applications in various fields, such as antennas, microwave filters, optical filters, absorbers, polarizers, and the like. However, no one is used on energy-saving glass, and it is even less likely to provide good wireless communication quality. But it does not reduce the effect of energy saving. Therefore, a new frequency selection plane structure is needed to solve the above problem.

The object of the present invention is to provide a frequency selective planar structure for selecting a microwave permeable frequency band, the structure comprising: a metal layer; an array structure having a plurality of arrays of microcells, each microcell comprising one a first main slot, located on the metal layer, for transmitting microwaves in a first working frequency band; wherein the first main slot has two first main body linear slots intersecting to form a cross shape A main body slot and four first end linear slots are respectively located at four ends of the main body slot, each first main body linear slot has a first body width W1 and a first body length L1, each of the first An end linear slot has a first end width W2 and a first end length L2. When the metal oxide layer on the energy-saving glass has the structure, the first working frequency band can be maintained in good wireless communication, and the energy-saving effect of the energy-saving glass can be maintained.

Another object of the present invention is to provide a slot structure on a metal layer for selecting a microwave permeable frequency band, comprising: a first main slot on the metal layer for making a Microwave penetration of the first working frequency band; and a plurality of second main slots located on the metal layer for microwave penetration in a second operating frequency band; wherein the first main slot has two A main body linear slot intersects to form a cross-shaped first main body slot and four first end linear slots are respectively located at four ends of the main body slot, the first main body linear slot has a first body width W1 And a first body length L1, the first end linear slot has a a first end width W2 and a first end length L2; wherein the plurality of second main slots each have two second body linear slots intersecting to form a cross-shaped second body slot and four second ends The linear slots are respectively located at a plurality of ends of the main slot, the second main linear slot has a second body width W3 and a second body length L3, and the second end linear slot has a second end width W4 With a second end length L4. When a plurality of the slot structures are arranged in an array on the metal oxide layer of the energy-saving glass, the first and second working frequency bands can be maintained in good wireless communication, and the energy-saving effect of the energy-saving glass is maintained.

(1) ‧‧‧glass

(2) ‧‧‧ metal layer

(3) ‧ ‧ energy-saving glass

(4) ‧‧‧ slots

(5) ‧‧‧microcells

(6) ‧‧‧frequency selection plane structure

(20)‧‧‧microcells

(21)‧‧‧Energy-saving glass

(211)‧‧‧metal layer

(212) ‧‧‧glass

(43) ‧‧‧First main slot shape

(431)‧‧‧First body slot

(432)‧‧‧First end linear slot

(44)‧‧‧Second main slot shape

(441)‧‧‧Second main slot

(442)‧‧‧Second end linear slot

(511, 512, 521, 522, 531, 532, 541, 542) ‧ ‧ reflection loss value

L1, L1’‧‧‧ first body length

W1, W1’‧‧‧ first body width

L2, L2'‧‧‧ first end length

(23)‧‧‧First main slot shape

(231)‧‧‧First body slot

(232)‧‧‧First end linear slot

(31, 32, 33) ‧ ‧ reflection loss values

(40) ‧‧‧microcells

(41)‧‧‧Energy-saving glass

(411)‧‧‧metal layer

(412) ‧‧‧glass

W2, W2’‧‧‧ first end width

T, T’‧‧‧ glass thickness

t, t’‧‧‧metal layer thickness

P, P’‧‧‧ microcell length

L3‧‧‧Second body length

W3‧‧‧Second body width

L4‧‧‧second end length

W4‧‧‧second end width

1 is a schematic view of a preferred embodiment of the present invention.

Fig. 2(A) is a plan view showing a microcell structure and an energy-saving glass of the present invention.

Figure 2 (B) is a side view of a microcell structure and energy saving glass of the present invention.

Fig. 3(A) is a graph showing the results of reflection loss of the first preferred embodiment of the present invention.

Figure 3 (B) is a graph showing the results of reflection loss of a second preferred embodiment of the present invention.

Figure 3 (C) is a graph showing the results of reflection loss of general energy-saving glass.

Figure 4 (A) is a plan view of another microcell of the present invention and the energy saving glass.

Figure 4 (B) is a side view of another micro unit of the present invention and the energy-saving glass Figure.

Figure 5 (A) is a graph showing the results of reflection loss of a third preferred embodiment of the present invention.

Figure 5 (B) is a graph showing the results of reflection loss of a fourth preferred embodiment of the present invention.

Figure 5 (C) is a graph showing the results of reflection loss of the fifth preferred embodiment of the present invention.

Figure 5 (D) is a graph showing the results of reflection loss of a sixth preferred embodiment of the present invention.

1 is a schematic view of the present invention for use on a metal oxide layer of an energy-saving glass. As shown in FIG. 1, a surface of a glass (1) is coated with a metal layer (2) to form an energy-saving glass (3). The metal layer (2) has a plurality of slots (4), and the slots (4) form a microcell (5), and the plurality of microcells (5) are successively arranged in an array to form a frequency selective plane. Structure (6). It should be noted that the present invention is not limited to use on the metal layer (2) of the energy-saving glass (3), and is not limited to use on the energy-saving glass (3). The slot (4) of the present invention and its composition can also be applied to A printed circuit board or the like is commonly used as a substrate for a microwave transfer structure, such as an FR4 plate having a metal oxide layer, etc., but in order to clarify the description of the present invention, the following description refers to an energy-saving glass (3) and a metal oxide layer ( 2) As an example.

2(A) and 2(B) are structural diagrams of a micro-cell (20) according to an embodiment of the present invention, the micro-cell (20) being located on a metal layer (211) of an energy-saving glass (21), wherein Figure 2 (A) is a top view of the micro-cell (20), and Figure 2 (B) For the side view of the energy-saving glass (21), the energy-saving glass (21) is composed of a metal layer (211) and a glass (212), as shown in Fig. 2(A), the metal layer (211) has a first main slot shape (23), the first main slot shape (23) is formed by a plurality of different sub-slots, the different sub-slots can be divided into two different slots, One of the two main body linear slots is orthogonal to each other to form a cross-shaped first main body slot (231), and the two first main body linear slots are preferably the same size, the first main body slot (231) is preferably located in the center of the microcell (20), but it may also be offset from the center of the microcell (20) without limitation. The other auxiliary slot is formed by four first end linear slots (232), and the first end linear slots (232) are respectively connected to the four ends of the first body slot (231), preferably The four first end linear slots (232) are all the same size, but are not limited thereto. Preferably, the midpoints of the first end linear slots (232) are each perpendicularly connected to the four ends of the first body slot (231), but are not limited thereto. Further, the microcell (20) is preferably in a square shape and has a side length P. In order to make the description more detailed, the present invention will be further described in the above preferred case. The first body linear slots forming the first body slot (231) each have a first body width W1 and a first body length L1, and the first end linear slots (232) each have A first end width W2 and a first end length L2, in general, L1 may be greater than L2, but L2 may also be greater than L1 such that the first main slot forms a square shape.

As shown in the side view of the energy-saving glass (21) of FIG. 2(B), the glass (212) has a glass thickness T, and the metal layer (211) has a metal layer thickness t, and the glass (212) is a common The glass has a relative dielectric constant ε _{r of} preferably 6.9, but is not limited thereto. Other glasses having a relative dielectric constant are also suitable for use in the present invention. The metal layer (211) is preferably a metal oxide coating film. The material coating film is preferably formed using Indium Tin Oxide (ITO) having a relative dielectric constant ε _r of 1, but is not limited thereto. Preferably, the glass (212) has a thickness T of 6 millimeters (mm) and the metal layer (211) has a thickness t of 0.1 micrometers (μm).

Referring to Figures 1, 2(A) and 2(B) together, the various parameters of the microcell (20) are related to their operating frequency bands, i.e., the parameters are related to the wireless communication frequency band in which the present invention is intended to maintain good quality. In a preferred case, the parameters may be defined as follows: the side length P of the microcell (20) is based on a center wavelength of the operating frequency band of 1/4 wavelength in the air; the first body length L1 and The sum L1+L2 of the first end length L2 is based on a 1/2 wavelength in air less than the center frequency of the operating frequency band; the first body width W1 is divided by the value W1/L1 of the first body length L1 or The first end width W2 is divided by the value W2/L1 of the first body length L1 to be close to 1/10.

In a plurality of preferred embodiments, the center frequency of the operating band is 2.45 GHz, the side length P of the microcell (20) is 34 millimeters (mm), and the thickness of the glass (212) is 6 mm (mm), the metal layer (211) has a thickness of 0.1 micrometer (μm). In the first preferred embodiment, the first body length L1 is 20 millimeters (mm), and the first body width W1 is It is 2 millimeters (mm), and the first end length L2 is 24 millimeters (mm), and the first end width W2 is 2 millimeters (mm). In a second preferred embodiment, the first body length L1 is 20 millimeters (mm), the first body width W1 is 2 millimeters (mm), and the first end length L2 is 22 millimeters ( Mm) to 24 mm (mm), the The first end width W2 is 2 millimeters (mm). The above parameter values are only examples, and other parameter values may be used in the present invention, as long as the parameter values meet the foregoing definitions, for example, W1/L1 must be close to 1/10 or the like. Thereby, when the frequency selective structure (6) having an array of several microcells (20) is located in the metal layer (2) of the energy-saving glass (3), the structure (6) can make the operating frequency band 2.45 GHz. The left and right wireless communication signals pass through the structure, and the signals of other working frequency bands cannot pass through the structure, thereby achieving a good wireless communication quality of 2.45 GHz.

3 is a graph showing the reflection loss results of the above embodiment, and FIG. 3(A) is a graph showing the results of the first preferred embodiment. It can be seen that the reflection loss value (31) at 2.45 GHz is close to -10 dB ( dB). Figure 3 (B) is a result of the second preferred embodiment, showing that the reflection loss value (32) at 2.45 GHz is close to -10 in the case of L2 = 22 mm or L2 = 24 mm. Decibel (dB). Figure 3 (C) shows the reflection loss value (33) of the general energy-saving glass (that is, the metal layer does not have any slot structure). It can be seen that the reflection loss is almost zero in any frequency band, indicating that there is no frequency band available for wireless. Signal penetration. From this, it can be seen that the first and second preferred embodiments can achieve good transmission quality for wireless signals operating at frequencies around 2.45 GHz.

4 is a structural diagram of different microcells according to another embodiment of the present invention. The microcell (40) is also located on a metal layer (411) of an energy-saving glass (41), wherein FIG. 4(A) is the microcell ( 40) a top view of the energy-saving glass (41), and FIG. 4 (B) is a side view of the energy-saving glass (41), the energy-saving glass (41) is composed of a metal layer (411) and a glass (412) As shown in FIG. 4(A), the metal layer (411) has a first main slot shape (43), and the first main slot shape (43) The system is composed of a plurality of different auxiliary slots, and the different auxiliary slots can be divided into two different slots, one of which is formed by two first main linear grooves orthogonal to each other to form a cross shape. The first main body slot (431), the two main body linear slots are preferably the same size, and the first main body slot (431) is preferably located in the center of the micro unit (40), but it can also Deviation from the center of the microcell (40) is not limited thereto. The other auxiliary slot is formed by four first end linear slots (432), and the first end linear slots (432) are respectively connected to the four ends of the first main body slot (431), preferably The four first end linear slots (432) are all the same size, but are not limited thereto. Preferably, the midpoints of the first end linear slots (432) are each perpendicularly connected to the four ends of the first body slot (431), but are not limited thereto. Further, the microcell (40) is preferably in a square shape and has a side length P'. In order to make the description more detailed, the present invention will be further described in the above preferred case. The first body linear slots forming the first body slot (431) each have a first body width W1' and a first body length L1', and the first end linear slots (432) Each has a first end width W2' and a first end length L2'. In addition, the metal layer (411) further has four second main slot shapes (44), and the four second main slot shapes (44) are preferably the same as the first main slot shape (43). The first main body slots (431) are centered, respectively located at the upper right, lower right, upper left, and lower left of the first main slot shape (43), and the positions may correspond to each other. The second main slot shapes (44) each have two second body linear slots intersecting to form a cross-shaped second body slot (441) and four second end linear slots (442) are respectively located in the body a plurality of ends of the slots, the second body linear slots having a second main The body width W3 and a second body length L3, the second end linear slot (442) has a second end width W4 and a second end length L4. The second main slots (44) are preferably of the same size and shape, but are not limited thereto. The first main slot shape (43) is larger than the second main slot shapes (44), whereby the first main slot shape (43) is used to select a lower frequency band to act on the The wireless signal of the frequency band passes, and the second main slot shape (44) is used to select a higher frequency band such that an infinite signal acting on the frequency band passes through the structure. It can be seen that the present invention can provide good wireless communication quality in dual frequency bands.

Figure 4 (B) is a side view of the energy-saving glass (41), similar to Figure 2 (B), the glass (412) also has a glass thickness T', the metal layer (411) has a metal layer thickness t' The glass (412) is a common glass, and its relative dielectric constant ε _{r is} preferably 6.9, but is not limited thereto, and other glass having a relative dielectric constant is also suitable for use in the present invention, and the metal layer (411) is preferably In the metal oxide plating film, the metal oxide plating film is preferably formed using Indium Tin Oxide (ITO) having a relative dielectric constant ε _r of 1, but is not limited thereto. Preferably, the glass (412) has a thickness T' of 6 millimeters (mm), and the metal layer (411) has a thickness t' of 0.1 micrometer (μm).

Referring to Figures 1, 4(A) and 4(B) together, the various parameters of the microcell (40) are related to their operating frequency bands, i.e., the parameters are related to the wireless communication frequency band in which the present invention is intended to maintain good quality. In a preferred case, the parameters may be defined as follows: the side length P' of the microcell (40) is based on a center wavelength of the operating frequency band of 1/4 wavelength in the air; the first body length L1 'The sum of the first end length L2' L1' + L2' is smaller than the double The center frequency of the lower frequency band in the frequency band is a principle of 1/2 wavelength in air; the sum of the second body length L3 and the second end length L4 L3+L4 is smaller than the center frequency of the lower frequency band in the dual frequency band The 1/2 wavelength in the air is a principle; the first body width W1 is divided by the value W1/L1 of the first body length L1 or the first end width W2 divided by the value W2/L1 of the first body length L1 to Nearly 1/10 is the principle; the first body width W3 is divided by the value W3/L3 of the first body length L3 or the first end width W4 is divided by the value W4/L3 of the first body length L3 to be close to 1/ 10 is the principle.

In a plurality of preferred embodiments, the center frequency of the lower operating band is 2.45 GHz, the center frequency of the higher operating band is 5.8 GHz, and the edge of the microcell (40) The length P' is 34 millimeters (mm), the glass (412) has a thickness of 6 millimeters (mm), and the metal layer (411) has a thickness of 0.1 micrometers (μm). In the third preferred embodiment of the present invention, The first body length L1' is 20 millimeters (mm), the first body width W1' is 2 millimeters (mm), and the first end length L2' is 24 millimeters (mm), the first end width W2 'The system is 2 mm (mm), the second body length L3 is 5 mm (mm), the second body width W3 is 2 mm (mm), and the second end length L4 is 4 mm. (mm), the second end width W4 is 1.5 millimeters (mm). In a fourth preferred embodiment of the present invention, the first body length L1' is 20 millimeters (mm), and the first body width W1' is 2 millimeters (mm). The first end length L2' is It may be 22 millimeters (mm) to 24 millimeters (mm), the first end width W2' is 2 millimeters (mm), and the second body length L3 is 5 millimeters (mm), the second body width W3 is 2 mm (mm), and the second end length L4 is 4 mm (mm), etc. The second end width W4 is 1.5 millimeters (mm). In a fifth preferred embodiment, the first body length L1' is 20 millimeters (mm), and the first body width W1' is 2 millimeters (mm). The first end length L2' can be 24 mm (mm), the first end width W2' is 2 mm (mm), the second body length L3 is 4.2 mm (mm) to 5 mm (mm), the second body width W3 It is 2 millimeters (mm), and the second end length L4 is 4 millimeters (mm), and the second end widths W4 are 1.5 millimeters (mm). In a sixth preferred embodiment, the first body length L1' is 20 millimeters (mm), and the first body width W1' is 2 millimeters (mm), and the first end length L2' is 24 In millimeters (mm), the first end width W2' is 2 millimeters (mm), the second body lengths L3 are 5 millimeters (mm), and the second body widths W3 are 2 millimeters (mm). The second end lengths L4 are 4 millimeters (mm), and the second end widths W4 are 1.5 millimeters (mm) to 1.9 millimeters (mm). The above parameter values are merely examples, and other parameter values may be employed in the present invention as long as the parameter values conform to the aforementioned definitions, for example, W1'/L1' must be close to 1/10 or the like. Thereby, when the frequency selective structure (6) having an array of several microcells (40) is located in the metal layer (2) of the energy-saving glass (3), the structure (6) can make the operating frequency band 2.45 GHz. The wireless communication signal with about 5.8 GHz passes through the structure, and the signals of other working frequency bands cannot pass through the structure, thereby achieving good wireless communication at 2.45 GHz and 5.8 GHz. quality.

5 is a graph showing the reflection loss results of the above embodiment, and FIG. 5(A) is a graph showing the results of the third preferred embodiment. It can be seen that the reflection loss value (511) at 2.45 GHz is close to -10 dB ( dB), reflection at 5.8 GHz The loss value (512) is close to -3 dB (dB). Figure 5 (B) is a result of the fourth preferred embodiment, showing the reflection loss at 2.45 GHz regardless of L2 = 22 mm (mm) or L2 = 24 mm (mm). The values (521) are both close to -10 decibels (dB), and the reflection loss values (522) at 5.8 GHz are less than -3 decibels (dB). Figure 5 (C) is a result of the fifth preferred embodiment, showing the reflection loss at 2.45 GHz regardless of L3 = 4.2 mm (mm) or L3 = 5 mm (mm). The values (531) are both close to -10 decibels (dB), and the reflection loss values (532) at 5.8 GHz are less than -3 decibels (dB). Figure 5 (D) is a result view of the sixth preferred embodiment, showing the value of the reflection loss at 2.45 GHz (W) in the case of W4 = 1.5 mm (mm) or 1.9 mm (mm) ( 541) are close to -10 decibels (dB), and the value of the reflection loss (542) at 5.8 GHz is less than -3 decibels (dB). Compared with the reflection loss result value (33) of the general energy-saving glass of Fig. 3 (C), that is, the metal layer does not have any slot structure, it can be seen that the above preferred embodiment can achieve an operating frequency of 2.45 GHz (GHz). ) Maintains good transmission quality with wireless signals near 5.8 GHz.

In a preferred embodiment, the microcell slot structures are arranged in an array structure having a size of 35.6% of the surface area of the glass used, that is, the array structure only needs to occupy 35.6% of the surface area of the glass to achieve a good wireless. Communication quality.

The present invention provides a microcell slot structure (5) and is arranged by a plurality of such microcell structures (5) to form an array structure (6), the array structure (6) being located on the surface metal of the energy saving glass (3) On layer (2), wherein the microcell structures (5) can be mainly divided into two types of structures, the first type enables wireless signals operating at 2.45 GHz to penetrate the energy-saving glass (3) ) and in and out The building using the energy-saving glass (3), and the second type enables wireless signals operating at 2.45 GHz and 5.8 GHz to penetrate the energy-saving glass (3) for access and use. Glass (3) buildings, thereby achieving good wireless communication quality. In addition, the array structure (6) occupies less than half of the energy-saving glass surface area (3), thereby not having too much impact on its energy-saving function.

The above-mentioned embodiments are merely examples for convenience of description, and the scope of the claims is intended to be limited to the above embodiments.

(40) ‧‧‧microcells

(41)‧‧‧Energy-saving glass

(411)‧‧‧metal layer

(412) ‧‧‧glass

(43) ‧‧‧First main slot shape

(431)‧‧‧First body slot

(432)‧‧‧First end linear slot

(44)‧‧‧Second main slot shape

(441)‧‧‧Second main slot

(442)‧‧‧Second end linear slot

L1’‧‧‧first body length

W1’‧‧‧ first body width

L2’‧‧‧first end length

W2’‧‧‧first end width

T’‧‧‧ glass thickness

T’‧‧‧metal layer thickness

P’‧‧‧microcell side length

L3‧‧‧Second body length

W3‧‧‧Second body width

L4‧‧‧second end length

W4‧‧‧second end width

Claims (14)

A frequency selective planar structure for selecting a frequency band through which a microwave can be penetrated, the structure comprising: a metal layer; an array structure having a plurality of arrays of microcells, each microcell comprising: a first major slot, It is located on the metal layer for transmitting microwaves in a first working frequency band; a plurality of second main slots are located on the metal layer for penetrating microwaves in a second operating frequency band; The first main slot has two first main body linear slots intersecting to form a cross-shaped first main body slot and four first end linear slots are respectively located at four ends of the main body slot, the first main body The linear slot has a first body width W1 and a first body length L1. The first end linear slot has a first end width W2 and a first end length L2. The first main slot is located in the metal layer. The center of the first main slot is centered on the first main slot of the first main slot, and is located at the upper right, the lower right, the upper left and the lower left of the first main slot, and the micro is Length of unit At 2.45 gigahertz (GHz) frequency length of 1/4 wavelength in the air. The frequency selective planar structure according to claim 1, wherein the plurality of second main slots each have two second body linear slot holes intersecting to form a cross-shaped second body slot and four Two ends The linear slots are respectively located at a plurality of ends of the main slot, the second main linear slot has a second body width W3 and a second body length L3, and the second end linear slot has a second end width W4 With a second end length L4. The frequency selection plane structure as described in claim 2, wherein the first working frequency band is lower than the second working frequency band. The frequency selective planar structure of claim 2, wherein the positions of the four second main slots are respectively corresponding to the first main body slots. The frequency selective planar structure of claim 1, wherein the sum of the first body length L1 and the first end length L2 is less than a half wavelength length in the air at a frequency of 2.45 GHz. The frequency selective planar structure of claim 5, wherein the sum of the second body length L3 and the second end length L4 is less than a half wavelength length in the air at a frequency of 5.8 GHz. The frequency selective planar structure of claim 6, wherein the sum of the second body length L3 and the second end length L4 is less than a half wavelength length in the air at a frequency of 5.8 GHz. The frequency selective planar structure of claim 7, wherein the sum of the second body length L3 and the second end length L4 is less than a half wavelength length in the air at a frequency of 5.8 GHz. The frequency selective planar structure of claim 8, wherein the first body width W1 or the first end width W2 divided by the first body length L1 is close to 1/10. The frequency selective planar structure according to claim 9, wherein the second body width W3 or the second end width W4 divided by the second body length L1 is close to 1/10. The frequency selective planar structure of claim 1, wherein the metal layer is placed on a glass. The frequency selective planar structure of claim 1, wherein the metal layer has a thickness of 0.1 micrometer (μm). a slot structure on a metal layer for selecting a frequency band through which the microwave can be penetrated, comprising: a first main slot on the metal layer for allowing microwave penetration in a first working frequency band; And a plurality of second main slots on the metal layer for penetrating microwaves in a second working frequency band; wherein the first main slot has two first body straight slots to form a cross The first main body slot and the four first end linear slots are respectively located at four ends of the main body slot, and the first main body linear slot has a first body width W1 and a first body length L1. The first end linear slot has a first end width W2 and a first end length L2; wherein the plurality of second main slots each have two second body linear slots intersecting to form a cross-shaped second body The slot and the four second end linear slots are respectively located at a plurality of ends of the main slot, the second main linear slot has a second body width W3 and a second body length L3, the second end linear slot Hole has one Two tip width W4 and a length L4 of the second end, the first main slot situated at the center of the metal layer, the first four The two main slots are centered on the first main body slot of the first main slot, respectively located at the upper right, lower right, upper left and lower left of the first main body slot, and the length of the micro unit is close to 2.45 吉The Hertz (GHz) frequency is 1/4 wavelength in air. The slot structure according to claim 13, wherein the first body length L1 is 20 millimeters (mm), and the first body width W1 is 2 millimeters (mm), and the first end length L2 is 22 mm (mm) to 24 mm (mm), the first end width W2 is 2 mm (mm), the second body length L3 is 5 mm (mm), and the second body width W3 is 2 mm (mm), the second end length L4 is 4 mm (mm), and the second end width W4 is 1.5 mm (mm).